检索结果-南通市图书馆

欧拉-伯努利直梁弯曲振动内力解的一种新形式

在线全文

学校读者我要写书评

暂无评论

力学与实践 2024年第1期46卷 170-174页

作者：郝志伟刘荣刚陈再现哈尔滨工业大学海洋工程学院山东威海264209

针对欧拉-伯努利直梁受简谐载荷作用下的弯曲振动问题,在得到响应后再次采用达朗贝尔原理,给出了一种新形式的弯曲振动内力解,该解直观显示了简谐力和惯性力对弯曲振动内力的贡献。基于傅里叶级数严格证明了其与教材中利用梁挠曲线近似... 详细信息

针对欧拉-伯努利直梁受简谐载荷作用下的弯曲振动问题,在得到响应后再次采用达朗贝尔原理,给出了一种新形式的弯曲振动内力解,该解直观显示了简谐力和惯性力对弯曲振动内力的贡献。基于傅里叶级数严格证明了其与教材中利用梁挠曲线近似微分方程和弯曲内力微分关系求出的内力完全等价,为加深理解及应用傅里叶级数、静力学理论、达朗贝尔原理和梁弯曲理论提供了一个综合性较高的案例,期望能助力提升基础力学教学效果。

关键词：欧拉-伯努利梁弯曲内力达朗贝尔原理傅里叶级数

Full-State-Constrained Non-Certainty-Equivalent Adaptive Control for Satellite Swarm Subject to Input Fault

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2022年第3期9卷 482-495页

作者： zhiwei hao Xiaokui Yue haowei Wen Chuang Liu National Key Laboratory of Aerospace Flight Dynamics School of AstronauticsNorthwestern Polytechnical UniversityXi’an 710072China IEEE

Satellite swarm coordinated flight(SSCF)technology has promising applications,but its complex nature poses significant challenges for control *** response,this paper proposes an easily solvable adaptive control scheme to achieve high-performance trajectory tracking of the SSCF system subject to actuator efficiency losses and external *** existing adaptive controllers based on the certaintyequivalent(CE)principle show unpredictability and nonconvergence in their online parameter *** overcome the above vulnerabilities and the difficulties caused by input failures of SSCF,this paper proposes an adaptive estimator based on scaling immersion and invariance(I&I),which reduces the computational complexity while improving the performance of the parameter ***,a barrier Lyapunov function(BLF)is applied to satisfy both the boundedness of the system states and the singularity avoidance of the *** is proved that the estimator error becomes sufficiently small to converge to a specified attractive invariant manifold and the closed-loop SSCF system can obtain asymptotic stability under full-state ***,numerical simulations are performed for comparison and analysis to verify the effectiveness and superiority of the proposed method.

关键词： Dynamic scaling full-state constraints input faulttolerance non-CE adaptive control satellite swarm

基于空间句法的路易斯·巴拉甘色彩设计策略研究——以巴拉甘自宅和吉拉迪住宅为例

在线全文

学校读者我要写书评

暂无评论

新建筑 2024年第1期 64-69页

作者：郝志伟李懿芹王新博曹尚太原理工大学建筑学院太原030024

路易斯·巴拉甘建筑中的色彩多样而富有诗意,为探索其建筑设计中的色彩运用策略,借助空间句法分析工具Depthmap,以巴拉甘自宅和吉拉迪住宅为样本,量化探讨其色彩设计策略与规律。研究发现,巴拉甘的色彩设计与庭院空间密切相关,在营造空... 详细信息

路易斯·巴拉甘建筑中的色彩多样而富有诗意,为探索其建筑设计中的色彩运用策略,借助空间句法分析工具Depthmap,以巴拉甘自宅和吉拉迪住宅为样本,量化探讨其色彩设计策略与规律。研究发现,巴拉甘的色彩设计与庭院空间密切相关,在营造空间特征和引导空间叙事方面发挥了重要作用。此外,巴拉甘还将墨西哥本土文化元素融合到色彩和空间设计中,体现了他对地域文化的深度挖掘和创新诠释。

关键词：路易斯·巴拉甘建筑色彩空间叙事空间句法庭院空间巴拉甘自宅吉拉迪住宅

维普期刊数据库博看期刊

Globularization Mechanism and Near Isotropic Properties in Subcritical Heat‑Treated Ti6Al4V Fabricated by Directed Energy Deposition

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2023年第6期36卷 937-948页

作者： Guohao Zhang zhiwei hao Meng Wang Xufei Lu Zhuang Zhao Qian Wang Xin Lin Jing Chen Weidong Huang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China MIIT Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design Northwestern Polytechnical UniversityXi’an 710072China International Center for Numerical Methods in Engineering Universidad Politecnica de Cataluna08034 BarcelonaSpain Institute of Machinery Manufacturing Technology China Academy of Engineering PhysicsMianyang 621054China

Microstructure with globularαphase is desirable as it contributes to preferable comprehensive mechanical properties for titanium ***,titanium alloys fabricated by directed energy deposition(DED)are mainly characterized by the lamellarαphase within the basket-weave microstructure,which often leads to severe anisotropy and inferior low cycle fatigue(LCF)*** address this,the subcritical annealing and the cyclic annealing were applied to DED Ti–6Al–4V in order to achieve the transformation from the lamellarαphase to the globularα*** microstructural characteristics and the globularization behavior ofαphase during heat treatment were *** results show that the aspect ratio ofαis significantly decreased with the subcritical annealing due to the coarsening of lamellarα.Furthermore,the globularαis obtained with the cyclic annealing as a combination result of the termination dissolution and the side surface growth of the lamellarα.These contribute to a pronounced reduction of 85.4%in the ductility anisotropy,compared with the as-built specimens,and superior comprehensive mechanical properties including LCF are achieved with the formation of globularα.

关键词： Directed energy deposition Ti-6Al-4V Subcritical heat treatment Coarsening Globularization

老年腹股沟疝术后并发症风险列线图预测模型的建立及验证

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

腹腔镜外科杂志 2024年第6期29卷 451-456页

作者：张天昊郝志伟安杰李金李锦行姜战武保定市第一中心医院普通外二科河北保定071000 保定市第一中心医院产科河北保定071000

目的:建立老年腹股沟疝患者行腹腔镜经腹腹膜前疝修补术后并发症发生的列线图预测模型。方法:回顾分析2021年1月至2023年1月为254例老年腹股沟疝患者行腹腔镜经腹腹膜前疝修补术的围手术期资料,术后至少随访6个月,采用二元Logistic回归... 详细信息

目的:建立老年腹股沟疝患者行腹腔镜经腹腹膜前疝修补术后并发症发生的列线图预测模型。方法:回顾分析2021年1月至2023年1月为254例老年腹股沟疝患者行腹腔镜经腹腹膜前疝修补术的围手术期资料,术后至少随访6个月,采用二元Logistic回归分析探讨独立危险因素。再以独立危险因素构建可视化列线图模型,利用受试者工作特征曲线评价模型区分度、校准图评估模型校准度,绘制临床决策曲线分析临床获益能力。结果:254例患者均获得随访,其中33例发生并发症,发生率为12.99%。单因素分析结果显示,BMI、疝囊直径、难复性疝、疝环粘连程度、术中出血量与术后并发症相关(P24 kg/m2、疝囊直径>5 cm、难复性疝、疝环重度粘连、术中出血量>10 mL是术后并发症的独立危险因素。构建列线图预测模型,受试者工作特征曲线下面积为0.845,95%可信区间0.781~0.910,约登指数0.755,敏感度为0.879,特异度0.876,模型具有较高的预测价值。校正曲线显示预测值靠近理想曲线,一致性较好,在临床决策曲线中该模型的临床效能表现良好。结论:根据危险因素构建的列线图预测模型具有较高的区分度与校准度,有助于临床医生术前评估及术中操作,以尽早对高危患者进行预防与治疗。

关键词：疝,腹股沟腹腔镜检查老年人手术后并发症危险因素列线图预测模型

NEW DOOB'S MAXIMAL INEQUALITIES FOR MARTINGALES

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2023年第2期43卷 531-538页

作者：郝志伟李丽波 School of Mathematics and Computing Science Hunan University of Science and TechnologyXiangtan 411201China

Let 1≤q≤∞,b be a slowly varying function and letΦ:[0,∞)■[0,∞)be an increasing convex function withΦ(0)=0 and■Φ(r)=∞.In this paper,we present a new class of Doob’s maximal inequality on Orlicz-Lorentz-Karamata spaces LΦ,q,*** results are new,even for the Lorentz-Karamata spaces withΦ(t)=tp,the Orlicz-Lorentz spaces with b≡1,and weak Orlicz-Karamata spaces with q=∞in the framework of LΦ,q,b-Moreover,we obtain some even stronger qualitative results that can remove the△2-condition of Liu,Hou and Wang(Sci China Math,2010,53(4):905-916).

关键词： martingales Doob's inequality Orlicz-Lorentz-Karamata spaces convex functions

Approximate Solutions to the Hamilton-Jacobi Equations for Generating Functions

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2020年第2期33卷 261-288页

作者： hao zhiwei FUJIMOTO Kenji ZHANG Qiuhua Department of Astronautical Science and Mechanics Harbin Institute of TechnologyHarbin 150001China Department of Aeronautics and Astronautics Kyoto UniversityC3 Bldg.Kyotodaigaku-katsuraNishikyo-kuKyoto 615-8540Japan

For a nonlinear finite time optimal control problem,a systematic numerical algorithm to solve the Hamilton-Jacobi equation for a generating function is proposed in this *** algorithm allows one to obtain the Taylor series expansion of the generating function up to any prescribed order by solving a sequence of first order ordinary differential equations ***,the coefficients of the Taylor series expansion of the generating function can be computed exactly under a certain technical *** a generating function is found,it can be used to generate a family of optimal control for different boundary *** the generating function is computed off-line,the on-demand computational effort for different boundary conditions decreases a lot compared with the conventional *** is useful to online optimal trajectory generation *** examples illustrate the effectiveness of the proposed algorithm.

关键词： Generating functions Hamilton-Jacobi equations optimal control Taylor series expansion two-point boundary-value problems

Adaptation analysis and fusion correction method of CMIP6 precipitation simulation data on the Qinghai-Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第2期21卷 555-573页

作者： PENG hao QIN Dahui WANG Zegen ZHANG Menghan YANG Yanmei YONG zhiwei School of Civil Engineering and Geomatics Southwest Petroleum UniversityChengdu 610500China School of Geoscience and Technology Southwest Petroleum UniversityChengdu 610500China

In order to obtain more accurate precipitation data and better simulate the precipitation on the Tibetan Plateau,the simulation capability of 14 Coupled Model Intercomparison Project Phase 6(CMIP6)models of historical precipitation(1982-2014)on the Qinghai-Tibetan Plateau was evaluated in this *** indicate that all models exhibit an overestimation of precipitation through the analysis of the Taylor index,temporal and spatial statistical *** correct the overestimation,a fusion correction method combining the Backpropagation Neural Network Correction(BP)and Quantum Mapping(QM)correction,named BQ method,was *** this method,the historical precipitation of each model was corrected in space and time,*** correction results were then analyzed in time,space,and analysis of variance(ANOVA)with those corrected by the BP and QM methods,***,the fusion correction method results for each model were compared with the Climatic Research Unit(CRU)data for significance analysis to obtain the trends of precipitation increase and decrease for each *** results show that the IPSL-CM6A-LR model is relatively good in simulating historical precipitation on the Qinghai-Tibetan Plateau(R=0.7,RSME=0.15)among the uncorrected *** terms of time,the total precipitation corrected by the fusion method has the same interannual trend and the closest precipitation values to the CRU data;In terms of space,the annual average precipitation corrected by the fusion method has the smallest difference with the CRU data,and the total historical annual average precipitation is not significantly different from the CRU data,which is better than BP and ***,the correction effect of the fusion method on the historical precipitation of each model is better than that of the QM and BP *** precipitation in the central and northeastern parts of the plateau shows a significant increasing *** correlation coefficients between monthly

关键词： GCM CMIP6 Precipitation correction BP-QM fusion correction Spatio-temporal characteristics

Atmospheric iron deposition in a megacity of northwest China:Solubility,speciation,and deposition fluxes

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第7期90卷 383-393页

作者： Xiaotao Yang Pingping Liu zhiwei Xue hao Zhang Xuan Li Hongmei Xu Zhenxing Shen Department of Environmental Science and Engineering Xi'an Jiaotong UniversityXi'anChina State Key Laboratory of Loess and Quaternary National Key R&D of China Geology Institute of Earth EnvironmentChinese Academy of SciencesXi'anChina No.203 Research Institute of Nuclear Industry Xi'an710086China Xi'an Environmental Monitoring Station Xi'an 710054China

Atmospheric iron has crucial effects on biogeochemical cycles,atmospheric processing,global climate,and human *** this study,atmospheric dustfall samples were collected from six functional areas in Xi'an,China,from 2020 to *** spatiotemporal distributions and deposition fluxes of total and water-soluble(ws)Fe as well as the speciation and potential sources of ws-Fe were *** areas had the highest concentrations of total Fe and ws-Fe,which were mainly due to copious emissions of heavy metals during *** total Fe concentrations peaked in spring,primarily due to the substantial input of crustal dust,which also led to the lowest Fe solubility in this *** contrast,the highest levels of ws-Fe occurred during winter due to an increase in biomass *** the water-soluble forms,ws-Fe(II)was dominant and accounted for 74.8%of the total amount of *** dust was the main contributor to total Fe,whereas biomass burning primarily contributed to peak ws-Fe *** average total and ws-Fe deposition fluxes in Xi'an were the highest in spring and lowest in autumn,which were related to the distributions of the dustfall deposition fluxes and their Fe contents during these *** study provided a broader and comprehensive understanding of atmospheric iron deposition in Chinese urban area,which is of positive significance for understanding atmospheric chemistry and global climate change.

关键词： Atmospheric dustfall Iron Speciation distribution Seasonal variation Functional area Sources